Speed timer



2,877,454 SPEED TIMER V ifi v land, Ohio, a corporation of OhioApplication August 6, 1953, Serial No. 372,622 3Claims. or. 340-263) q qmore effective in curbing speeding in restrictedzones throughout a givenmunicipality than is the most vigilant andfimpartial conventionaltraflic patrol or radar patrol. 'Accordingly, it will be understood thatan lobjeet fof the invention is to provide aninexpensive andunusually,Mmm Zedlar, Mentor, and Allen Edwin Lenten-wickassignors to ZonealarmCorporation, .Cleveschool zone or other hazardous effective method ofcontrolling and curbing speeding,

and another object of the invention is the provision of simple versatileapparatus adapted for use under a variety of circumstances.

The invention will be more clearly understood from the followingdetailed description of one preferred form of apparatus contemplated bythe invention, together with the accompanying schematic drawing of suchpreferred form.

The invention may utilize any standard regular power supply for theapparatus such as a full wave rectifier, filter and voltage regulator,indicated as contained in a package 10. The invention may also utilizetwo switchactuated one-pulse multivibrators indicated as contained,respectively, within the packages 11 and 12. It will be appreciated thatthe actual packaging arrangement of the various elements is immaterial,the indicated packaging being chosen merely to facilitate thedescription of the invention. It will also be appreciated thatequivalents for the various elements or combinations of elements may beused, thus, for example, the power supply package 10 could be replacedby a self-contained battery unit or by other standard power supply unitssuited to the particular type of electrical supply available.

Thus, it will be understood that the following specific description ofthe presently preferred embodiment of the invention is made for thepurpose of most clearly and concisely disclosing the subject matter ofthe invention and the inclusion of the specific details of suchpreferred embodiment is not to be interpreted as limiting in any sensethe scope of the invention which is to be defined solely by the claimsappended hereto.

As shown schematically in the drawing, the invention may utilize a pairof pressure switches 13 and 14 of any suitable type, each of which isassociated with one of the air-tight hoses 15 and 16, such arrangementsbeing commonly used in trafiic survey work. The hoses are adapted to beplaced in a roadway in spaced relation to be momentarily compressed bypassing vehicle wheels so as to mo-- mentarily close their associatedswitches 13 and 14. The hoses are placed in such a relation to thedirection of is placed on the tube 20' which v Patented 7 Mar. 10, 1

trafiicthat the switch 13 is closed by passage of a vehicle priorto theclosing of the switch 14.

' The multivibrator circuits comprise four tubes 20, 21, 22, and 23. Thecathode of each'of these tubes is-coupled to the cathode bias resistor24.

"In the quiescent state (when no passing 'vehicles are actuatingswitches 13 and 14), tubes '21 and 23 are'conducting and tubes 20 and 22are cut off, this cut-01f "remaining stable dueto the relatively smallvoltage dr'op through resistors 26 and 27 to points 28 'a nd29as'coinpared to the drop through cathode bias resistor 24 durtube 2 2is not conducting, the platerel'ay coil 32 is not energized andits'normally open contact 33 prevents the alarm 'from operating.

, When a passing vehicle closes switch 13,3a zero bias immediatelyconducts.

The plate voltage offthis tube, therefore, drops suddenly ,and causesthe timingcondenser 35 to'start discharging througli resiis'tor 36 andrheostat 37. This discharge is sufiicient to' drive the coupled-grid ofthe tube 21 below cut-off and this tube immediately ceases to conduct,

.causing the voltage drop between point 38' and groundacross're'sisto'rs' 39 and 26 to approach power supply voltage, thuscausing the voltage drop across resistor 26 to increases'uifieiently tomaintain conduction of "the tube 20 even though the switch 13 reopens.

The 't'ube 21 rema'i' cut oif until its grid bias again drops-belowcut-olfvalve asdischarge from the'condenser 3 5 approaches completion,the time of cut-otf being varied by adjusting therheostat 37 to vary therate of" discharge of the condenser. Upon re-conduction of the tube 21,the voltage drop across the resistor 26 falls to its original value andthe tube 20 ceases to conduct. Thus, it will be seen that the tubes 20and 21 are employed in a onepulse multivibrator circuit, the triggeringimpulse being supplied by momentary closing of the switch 13.

The tubes 22 and 23 are employed in the second onepulse multivibratorcircuit 12, which only during its timing period energizes the platerelay 32, thereby closing its contact 33 and sounding the alar Thesecond multivibrator circuit 12 is almost identical to the first circuit11, but is triggered only by actuation of the switch 14 during thetiming period of the first circuit 11 when the voltage drop across theresistor 26 is sufficiently low to raise the grid of tube 22 abovecutoff. At other times closing of the switch 14 has no effect on thesystem.

Upon triggering of the second multivibrator circuit 12, the tube 22fires causing the condenser 40 to discharge, thus driving the grid oftube 23 below cut-off. This causes a sufiicient increase in voltage dropacross resistor 27 to cause the tube 22 to continue conducting for atimed period which may be varied by adjustment of the rheostat 41.

Thus, only if the switches 13 and 14 are actuated in sequence within atime interval not exceeding the timing period of multivibrator circuit11 will the relay coil 32 be energized and the alarm sounded, The longerthis timing period is made by increasing the resistance setting of therheostat 37, the lower will be the vehicle speed at which the alarm willsound provided the spacing between hoses 15 and 16 is not changed. Thelonger the timing period of multivibrator circuit 12 is made byincreasing the resistance setting of the rheostat 41, the longer thealarm will sound upon each speed violation.

In connection with the alarm, a thermal time relay comprising a heatingelement 42 and normally closed contacts 43 may be provided as aprotective measure to shut ofi the alarm after an extended period ofoperation should the relay 12 remain energized through some defect inthe circuit.

A time clock 44 of standard design may be provided having contacts 45which are closed only during the hours of the day of'week when operationofthedevice is desired. An indicator light 46 may be included toshowwhen the system as a whole is energized or deenergized by the timeclock 44.

In order to operate the alarm remotely and independently of the speedmeasuring system so that it may be utilized, for'instance, as part of acivil defensewarning. system, a separatecircuit independent of the timeclock 44 and the heat sensitive relay 42 is provided having switch 47 init which can be actuatedremotely for signal purposes independently ofthe normal control system.

, While the apparatus described in detail above has been found tobeparticularly suited to the broad objects. of

the invention, no holding relays or similar mechanical devices beingrequired and no moving parts being utilized in the timing circuit otherthan the road switches themselves, equivalent speed monitoring devicesdeparting in greater or smaller degree from the details of our specificdisclosure may occur to those familiar with the most closely relatedarts. This range of equivalents is intended to be covered by thefollowing claims which definethe scope of the invention.

What is claimed is:

l'. A speed monitoring .device comprisinga .pair of switchessuccessively actuatable by passing vehicles, a relaxation circuit having.a stable permanent phase and a stable temporary phase, saidcircuitbeingtriggered from 1 saidpermanent phase to said temporaryphasebyactuavtion of-only; acertain one ofsaid pair of. switches. andalarm means responsive to the actuation of the otherone of said switchesonly during said ternporaryrphase.

2. A speed monitoring device to monitor speed between a pair of pointscomprising a one-pulse multivibrator circuit, means responsive tovpassage of a vehicle past only a certain one of said pair of points totrigger said multivibrator circuit from its permanent to its temporaryphase, and alarm means responsive to the passage of said vehicle pastthe other one of said pair of points only during said temporary phaseof'said multivibrator circuit.

3. A speed monitoring device comprising a sub-circuit including anelectronic alarm actuating element in series with the plate circuitof anelectric valve"having"a'jcontrol electrode and a cathode, said controlelectrode-being normally'negatively biased below cut-'ofi with. respectto said cathode, means responsive to passage of a vehicle past a firstgivenpoint to establish during a first time period following saidpassage a source of positive bias sufficiently to drive said controlelectrode above cut-off with respect to said cathode, means tomomentarily3couple said source and said control electrode upon. passageof said vehicletpast a second given; point whereby said electricvalvewill conduct and said alarm.will-be actuated, and means to causesaid electric valve to con- .tinue to conductv during a second timeperiod following initial actuation. of said alarm whereby said alarmwillcontinue to beactuated during said second time period.

'ReferencesCited in the file of. thispatent' UNITED STATES PATENTS 12,284,850 Smith. 'June- 2,1942

